1. Field of the Invention
The present invention relates to an original-cover closer suitable for use with an original cover of a duplicator, copier, printing machine or the like (will be referred to as "copying machine" hereinunder) to open and close the original cover in relation to an original placed on a contact glass of the copying machine.
2. Description of the Prior Art
Of the original-cover closers having been proposed so far, a typical one comprises a mounting or base member to be installed on the body of a copying machine, a supporting member pivoted by a first hinge pin to the mounting member and on which an original cover of the copying machine is supported, a lifting member mounted by a second hinge pin to a free end of the supporting member to be pivotable in an opposite direction to the turning direction of the supporting member and to which the original cover is fixed, and an elastic member provided between the mounting and supporting members to elastically force the supporting member in the opening direction of the original cover.
In addition, another original-cover closer of the above type is also known which is adapted to allow the elastic member to act on a controlling member installed on the lifting member in order to turn the supporting member in the opening direction of the original cover while controlling the reverse turning of the lifting member. In this example, the acting point of the elastic member and the controlling member are not engaged on, or coupled to, each other so that when the lifting member is turned reversely, the acting point of the controlling member will slide on the elastic member while pressing down the latter, or the elastic member will not act in any other direction and will thus be expanded or compressed in a same direction as the direction in which the supporting member is opened or closed. More particularly, in the conventional original-cover closers, the lifting member includes two side plates between and in which a horizontally extending control pin is rotatably supported as a controlling member in a position off the position at which the side plates of the lifting member are pivoted to side plates of the supporting member. Thus the acting point of the elastic member is allowed to act on the control pin. Otherwise, guide slots are formed in the side plates of the supporting member in a position off the position at which the side plates of the lifting member are pivoted to the side plates of the supporting member. The control pin is supported movably in the guide slots and engaged on an engagement projection provided off the pivoted point of the lifting member.
In the former original-cover closer, when the lifting member is turned reversely, the control pin slides on the top of a slider provided over the elastic member to expand and compress the elastic member in a direction in which the elastic force of the elastic member acts on the supporting member. In the latter original-cover closer, as the lifting member is turned reversely, the control pin pressed by the engagement projection is guided in the guide slots to thus expand or compress the elastic member in a direction in which the elastic force of the elastic member will act on the supporting member. That is to say, in both these conventional original-cover closers, the acting direction of the elastic member will not change even when the lifting member is turned reversely.
In the above conventional original-cover closers, when the lifting member is turned reversely, the elastic member is expanded or compressed in a direction in which the supporting member is opened or closed. These conventional original-cover closers adapted such that the slider acting on the elastic member and a cam member abutting the slider provided over the mounting member are used to control the opening and closing operations of the original cover, are advantageous in that the elastic member will not sway when the lifting member is turned reversely, and thus the acting direction of the elastic member will not change. However, such a construction of the original-cover closers will not always be necessary for a original-cover closer which uses no such slider and cam member.